Physical activity, pregnancy and mental wellbeing : focus on women at risk for gestational diabetes

Physical inactivity, mental health problems and obesity, whilst interrelated, each represent a major global health challenge. Furthermore, obesity substantially contributes to the increasing prevalence of gestational diabetes mellitus (GDM), an emerging worldwide epidemic amongst pregnant women. Life events such as pregnancy may affect physical activity as well as mental well-being. This doctoral thesis systemically reviews the literature concerning the effects of life events, especially pregnancy, on physical activity, and examines mental wellbeing and physical activity in women at risk for GDM. The thesis also evaluates the effects of a randomised lifestyle intervention aimed at preventing GDM on self-rated health from early pregnancy throughout the first year following birth. The systematic review consisted of studies amongst healthy adults. In addition, this doctoral thesis includes participants from two randomised controlled trials: the Finnish Gestational Diabetes Prevention Study (RADIEL) and the Finnish Gestational Diabetes Prevention Study Part II: Autonomic Nervous System and Exercise (ANS-EXE). The participants consisted of 482 pregnant women and 39 women planning a pregnancy at high risk for GDM (a history of GDM or a prepregnancy body mass index [BMI] ≥ 29 kg/m2 or both), and 358 pregnant women in the general Finnish population. A proportion of the pregnant women at risk for GDM received diet and physical activity counselling from early pregnancy to one-year postpartum. The studies included in the systematic review showed statistically significant changes in leisure-time physical activity after life events. Changes varied according to different life events and the age and gender of the study population. Physical activity decreased both from prepregnancy to pregnancy, and from prepregnancy to the postpartum period. Pregnant women at risk for GDM exhibited higher Edinburgh Postnatal Depression Scale scores compared to pregnant women in the general population during early pregnancy, but this difference disappeared after adjusting for age, BMI and income. In addition, cardiorespiratory fitness, as assessed by measuring the maximal oxygen consumption (VO2max) during a cycle ergometer test, and self-reported leisure-time physical activity were positively associated with the self-rated general health and physical well-being domains of the 36-Item Short-Form Health Survey in women planning a pregnancy and at risk for GDM, which held when controlling for BMI. Furthermore, self-rated general health and physical well-being differed between those women with very poor or poor cardiorespiratory fitness. The self-rated health of women at risk for GDM tended to improve amongst the lifestyle counselling group and to deteriorate in the control group from pregnancy to one-year postpartum, although the difference between groups was not statistically significant. Life events affect leisure-time physical activity; for example, pregnancy tends to decrease physical activity levels. The prevalence of depressive symptoms during early pregnancy is higher amongst women at risk for GDM compared to women in the general pregnant population. The higher prevalence seems to be explained by characteristics such as age, BMI and income. Moreover, even a slightly better cardiorespiratory fitness could be beneficial for the health-related quality of life amongst women at risk for GDM who are planning a pregnancy. The effectiveness of lifestyle counselling for high-risk pregnant women aimed at improving self-rated well-being requires further research.